Synchronization of property values between a client and a server

ABSTRACT

A system is provided for synchronizing a property value between a proxy of an application of a client and a corresponding remote object of a server. The application instantiates a proxy of a proxy class corresponding to a remote object of a remote object class where the proxy class specifies a property with a proxy getter. The application sends to the server an invocation request message to invoke a remote object member function of a remote object and receives an invocation response message. When the invocation response message includes a property update, the application extracts from the invocation response message the value of the property from the property update and stores the extracted value in the proxy. When the proxy getter for the property is invoked, the value of the property can be retrieved from the proxy without having to send an invocation request message to the server.

This application is concurrently being filed as related U.S. applicationSer. No. 15/419,964, entitled “DEFERRING INVOCATION REQUESTS FOR REMOTEOBJECTS,” and U.S. application Ser. No. 15/420,001, entitled“OBJECT-ORIENTED REMOTE PROCEDURE CALLS FOR BROWSER APPLICATIONS,” bothof which are herein incorporated by reference in their entireties.

BACKGROUND

Cloud-based services are often provided via applications that areexecuted via a web browser. To develop such an application, a programmermay develop an application that is to be executed by a web browser of aclient and that accesses services of a server of a cloud data center.The application (or client code) typically provides a user interfacethrough which a user can access features of the application. Forexample, if the application is a word processor, then the applicationdisplays content of a document being edited, a menu bar for accessingfeatures of the word processor (e.g., open document and insertfootnote), and so on. The document that is being edited is stored on theserver. Thus, when the user requests to open the document, theapplication sends an open request to the server and receives a copy ofat least a portion of the document. The application displays content ofthe document. When a user makes a change to the document, theapplication may update the displayed content and send a message to theserver. The server then changes the document. The communications betweenthe client and the server typically are based on Representational StateTransfer (“REST”) or RESTful model such as Hypertext Transport Protocol(“HTTP”) request messages (e.g., a GET method) and response messages.

Such applications are typically written in JavaScript because mostbrowsers support the execution of JavaScript applications. The servercode, in contrast, is typically written in programming languages otherthan JavaScript, such as C# or C++, for efficiency reasons becauseJavaScript is an interpreted language and C# and C++ are compiled inexecutables. JavaScript and C# and C++ are object-oriented programminglanguages. An object-oriented programming language supports aprogramming model in which the program specifies classes that define thetypes of objects that can be instantiated. A class defines the datamembers and methods (also referred to as member functions) for theobjects of that class. Each method has a signature that specifies thename of the method, the types of input parameters to be passed to themethod, and the types of output parameters to be returned by the method.For example, a document class may be defined to include methods foropening a document, modifying the document, and saving the document.During execution of an application, after an object of a certain classis instantiated, the application can invoke a method of the object byspecifying a reference to the object, an indication of the method toinvoke, and the input parameters (if any) to be passed to the method.When the method completes, the method returns the output parameters (ifany).

Such applications have historically accessed services of a server usinga web service interface that is defined by a Web Services DescriptionLanguage (“WSDL”) or using some other type of a remote procedure call(“RPC”) mechanism. Unfortunately, there is little support forobject-oriented RPCs, also referred to as remote method invocations(“RMIs”), from such applications to servers. As a result, suchapplications often do not use an object-oriented approach when accessingobjects hosted by a server.

SUMMARY

A system is provided for an application executed by a client to invoke aremote object method of a remote object of a remote object class that ishosted by a server. The application instantiates a proxy of a proxyclass that includes a proxy member function with the same signature asthe remote object member function. The application associates an objectidentifier with the proxy. The application invokes the proxy memberfunction of the proxy. Under control of the invoked proxy memberfunction, the application sends to the server an invocation requestmessage that includes the object identifier that is associated with theproxy and an identifier of the remote object member function. Theapplication relies on functionality provided by the browser without theneed for the browser to access add-on functionality when executing theapplication.

A system is provided for synchronizing a property value between a proxyof an application of a client and a corresponding remote object of aserver. The application instantiates a proxy of a proxy classcorresponding to a remote object of a remote object class where theproxy class specifies a property with a proxy getter. The applicationsends to the server an invocation request message to invoke a remoteobject member function of a remote object and receives an invocationresponse message. When the invocation response message includes aproperty update, the application extracts from the invocation responsemessage the value of the property from the property update and storesthe extracted value in the proxy. When the proxy getter for the propertyis invoked, the value of the property can be retrieved from the proxywithout having to send an invocation request message to the server.

A system is provided for an application executing at a client to sendinvocation requests to remote objects of a server. Each invocationrequest is generated when the application invokes a proxy of a proxyclass of the application corresponding to a remote object of a remoteobject class. For each invocation request, when the invocation requestis deferrable, the system stores the invocation request. When theinvocation request is not deferrable, the system sends to the server aninvocation request message that includes each stored invocation requestnot previously sent and the current invocation request. The systemreceives invocation response messages from the server. For eachinvocation response of a received invocation response message, thesystem provides to the application an indication that the invocationresponse has been received.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram that illustrates data structures of anapplication and server component in some embodiments.

FIG. 2 is a flow diagram that illustrates the processing of a method ofa proxy that is synchronously invoked in some embodiments.

FIG. 3 is a flow diagram that illustrates the processing of a receiverequest component of a server component in some embodiments.

FIG. 4 is a flow diagram that illustrates the processing of an extractparameters method of a response object class for a response object of aclient component in some embodiments.

FIG. 5 is a flow diagram that illustrates the processing of a storeparameters method of a response object class for a response object of aserver component in some embodiments.

FIG. 6 is a flow diagram illustrating the processing of a retrieve IDmethod of an ID table object class in some embodiments.

FIG. 7 is a flow diagram that illustrates the processing of a retrievereference method of an ID table object in some embodiments.

FIG. 8 is a flow diagram that illustrates the processing of an add entrymethod of an ID table object that is passed a reference in someembodiments.

FIG. 9 is a flow diagram that illustrates the processing of an add entrymethod of an ID table object that is passed an entry in someembodiments.

FIG. 10 is a block diagram that illustrates an implementation of theOORPC system that supports peer hosting of remote objects in someembodiments.

FIG. 11 is a block diagram that illustrates data structures that supportsynchronization of values of properties by the OORPC system in someembodiments.

FIG. 12 is a flow diagram that illustrates the processing of a getproperty values component of a server component in some embodiments.

FIG. 13 is a flow diagram that illustrates the processing of a storeproperty values component of a client component in some embodiments.

FIG. 14 is a flow diagram that illustrates a code generator of the OORPCsystem for automatically generating code for proxy classes in someembodiments.

FIG. 15 is a flow diagram that illustrates the processing of a processproxy properties component of the code generator in some embodiments.

FIG. 16 is a flow diagram that illustrates the processing of a sendrequest component of a client component in some embodiments.

FIG. 17 is a flow diagram that illustrates the processing of a receiverequest component of a server component in some embodiments.

DETAILED DESCRIPTION

A method and system is provided for automatically generating code for anapplication executed by a client to access objects that are hostedremotely by a server or other remote device in an object-orientedmanner. The term “client” refers to a computing device, and the term“server” refers to a computing device. In some embodiments, anObject-Oriented Remote Procedure Call (“OORPC”) system inputs adefinition of the interfaces for the remote object classes for objectsthat are hosted remotely by the server (“remote objects”). For eachremote object class, the OORPC system automatically generates a proxyclass that serves as a proxy for the remote object class. A “proxy” isan object whose methods primarily send invocation request messages tothe server that hosts the corresponding remote object. There istypically a one-to-one correspondence between a proxy and a remoteobject. The proxy class has the same interface (e.g., the same methodsand method signatures) as the corresponding remote object class, butwith code that is different from the code of the remote object class.For each method of the proxy class, the OORPC system generates code forthat method that, when invoked, sends an invocation request message tothe server that hosts a remote object corresponding to the proxy of theproxy class. The invocation request message identifies the remoteobject, the method, and any input parameters passed to the method. TheOORPC system also generates code for the method that, after aninvocation response message is received from the remote device, returnsfrom the invocation of the method with any output parameters that wereidentified in the invocation response message. Alternatively, if theinvocation of a method is an asynchronous invocation, the OORPC systemincludes a client component to process the invocation response messagethat may not be part of the method, but rather part of a callback methodthat is to be invoked to signal the application that the execution ofthe method has completed.

In some embodiments, the OORPC system provides a client component forthe application that maps each proxy to its corresponding remote object.The application may have a create proxy corresponding to a create remoteobject that is used to instantiate remote objects. Each method of thecreate proxy may be invoked to instantiate a remote object of a certainremote object class. Each method sends an invocation request message toa server component, referred to as a “stub,” to invoke the correspondingmethod on the create remote object to instantiate a remote object of theremote object class. Each method also instantiates a proxy for theremote object and returns a reference to the proxy. For example, thecreate proxy may have a create document method that sends an invocationrequest message to the server component requesting invocation of thecreate document method of the create remote object to instantiate adocument remote object. The instantiated document remote object may beassigned an object identifier (by either the application or the servercode). The create document method of the create proxy also instantiatesa document proxy corresponding to the document remote object and maps areference to the document proxy (e.g., address of the document proxy) tothe object identifier. The create document method of the create proxythen returns the reference to the document proxy. When the applicationsubsequently invokes a method of the document proxy as indicated by thereference, that method uses its reference to retrieve the objectidentifier of the document remote object. That method then sends to theserver component an invocation request message as described above thatincludes the object identifier to identify the document remote object tothe server component.

When the server component receives an invocation request message, theserver component extracts from the invocation request message the objectidentifier, the method identifier, and any input parameters. The servercomponent retrieves a reference to the remote object that is identifiedby the object identifier and invokes the identified method passing theinput parameters. When the method returns, the server component sends aninvocation response message to the client that includes the objectidentifier, the method identifier, and any output parameters.

In some embodiments, the create proxy and the create remote object areinstantiated during initialization of the application and the servercomponent, respectively, independently of the other. That is, theapplication instantiates the create proxy without communicating with theserver component, and the server component instantiates the createremote object without communicating with the application. Theapplication and the server component both assign the same objectidentifier (e.g., predefined) to identify the create proxy and thecreate remote object so that when the application invokes a method ofthe create proxy, the invocation request message that is sent to theserver includes the object identifier of the create remote object. Afterthe server component invokes a method of the create remote object, theserver component is returned a reference to the newly created remoteobject. The server component then generates an object identifier for thenewly created remote object, maps the object identifier to thereference, and sends an invocation response message that includes theobject identifier and the method identifier of the method that wasinvoked. When the application receives the invocation response message,the application maps the object identifier to the reference to thecorresponding proxy. In this way, when a method of the correspondingproxy is subsequently invoked, the method can include the objectidentifier of the remote object in the invocation request message.

In some embodiments, the OORPC system may not send invocation requestsuntil a send invocation request message criterion is satisfied. When thesend invocation request message criterion is satisfied, the OORPC systemsends an invocation request message that includes each invocationrequest that has not yet been sent. For example, the methods of theproxy classes may be designated as deferrable or not deferrable (e.g.,via metadata associated with the interface for the remote object class).When the application invokes a method that is deferrable, the OORPCsystem generates an invocation request that includes the objectidentifier, the method identifier, and any input parameters and queuesthe invocation request. When the application invokes a method that isnot deferrable, the OORPC system sends an invocation request messagethat includes the queued invocation requests and an invocation requestfor the current invocation. The send invocation request messagecriterion may be satisfied when a non-deferrable method is invoked. Thesend invocation request message may similarly be satisfied when aninvocation request has been queued for a certain period, when a certainnumber of invocation requests are queued, when the application directsthat the invocation request message be sent, and/or so on.

When the server component receives an invocation request message withmultiple invocation requests, the server component processes theinvocation requests in the order in which they were queued. Aftercompletion of the invocation requests, the server component sends aninvocation response message that includes an invocation response foreach invocation request of the invocation request message. When theapplication receives the invocation response message, it processes theinvocation responses in order of their corresponding invocationrequests.

In some embodiments, the OORPC system provides support for storingvalues of properties of remote objects locally at a client. When theOORPC system generates a proxy class for a remote object class, theOORPC system generates getter methods (“getters”) for propertiesdifferently from other methods. The OORPC system generates a gettermethod that, rather than sending an invocation request message to theserver to retrieve the value of the property, retrieves a locally storedvalue for the property and returns the value. To ensure that the locallystored value for a property of a proxy is synchronized with the valuestored by the corresponding remote object, the server component mayappend to each invocation response message a property update for eachproperty of a remote object whose value has changed since the lastinvocation response message was sent. The server component may maintaina list of the values that were last sent for each property, and whensending an invocation response message, it may invoke the getter methodfor each property of each remote object to identify the values that havechanged.

When the application receives an invocation response message with aproperty update, the application stores the new value of the propertyupdate in the corresponding proxy. When the OORPC system generates theproxy classes from the interfaces of the remote object classes, theOORPC system may generate a store class for each proxy class. The storeclass may include a table that maps an identifier of each property(e.g., hash of the property name) to the type of the property (e.g.,integer) and a method of the store class for storing the value for thatproperty. The OORPC system may add to a proxy class a static data memberthat is a reference to a store object that is an instance store classfor that proxy class. When the OORPC system receives a new value for aproperty, it retrieves from the property update in the invocationresponse message the object identifier of the remote object, theidentifier of the property, and the value of the property. The OORPCsystem uses the object identifier to retrieve the reference to thecorresponding proxy and retrieves from that proxy the reference to thestore object. The OORPC system then invokes the store method of thestore object corresponding to the property passing the reference to theproxy and the value. The store method stores the value in the proxy.

FIG. 1 is a block diagram that illustrates data structures of anapplication and server component in some embodiments. A client 110executes an application 111, and a server 120 executes a servercomponent 121. The application and the server component are representedas pseudocode. During initialization, a client component 119 of theOORPC system executing at the client may instantiate an ID table object113, and the server component, which is a component of the OORPC system,may instantiate an ID table object 123. The ID table objects providemethods for storing and retrieving mappings of object identifiers ofproxies and remote objects to their corresponding references in an IDtable of the ID table objects. The application instantiates a createproxy 112, and the server component instantiates a corresponding createremote object 122. The client component adds to the ID table object 113a mapping of an object identifier (e.g., 1) for the create proxy to areference to (e.g., address of) the create proxy (“S”), and the servercomponent adds to the ID table object 123 a mapping of an objectidentifier for the create remote object to a reference to the createremote object. The server component then waits to receive invocationrequests from the client. The object identifier for a proxy of theclient and the object identifier for the corresponding remote object ofthe server have the same value.

To create a remote object of a remote object class, the applicationinvokes a method of the create proxy for creating remote objects of theremote object class. For example, if a remote object class is named “X,”the application may invoke a createX method of the create proxy tocreate a remote object of the remote object class X. The createX methodof the create proxy sends to the server an invocation request message(“req”) that includes an object identifier of the create remote object(“req.ID”), a method identifier of the createX method (“req.method”),and any input parameters (“req.inparam”). The client component mayinstantiate a request object 117 to store the data of an invocationrequest message to be sent and a response object 118 to store the dataof an invocation response message that is received. Similarly, theserver component may instantiate a request object 127 to store the dataof an invocation request message that is received and a response object128 to store the data of an invocation response message to be sent.

Upon receiving the invocation request message, the server componentextracts the object identifier from the invocation request message andinvokes a retrieve reference method (“retrieveref”) of its ID tableobject passing the object identifier to retrieve a reference to thecreate remote object. The server component then invokes an extractmethod (“extract”) of the request object to extract any input parameters(“inparam”). The server component then extracts from the request objectthe method identifier of the createX method. The server component thenuses the reference to the create remote object and the identifier of thecreateX method to invoke the createX method of the create remote objectpassing the input parameters. The createX method instantiates a remoteobject 124 (“X2 object”) of class X and returns an output parameter thatis a reference to the remote object 124. Although not illustrated by thepseudocode, the server component also invokes an add entry method of theID table object 123 to add to its ID table an entry that maps the objectidentifier (“2”) for the remote object 124 to the reference for theremote object 124 (“X2”) and adds to a response object (“res”) theobject identifier (“res.ID”) and the identifier of the createX method(“res.method”). The server component then invokes a store method(“store”) of the response object to store any output parameters. Theserver component then sends to the client an invocation response messagebased on the response object.

Upon receiving the invocation response message, the client componentinstantiates a response object based on the invocation response message.The client component then instantiates a proxy 114 (“X2 proxy”) andinvokes an add entry method of the ID table object 113 to add to its IDtable a mapping of the object identifier (“2”) for the proxy 114 to thereference for the proxy 114 (“X2”). If the invocation of the createXmethod was synchronous, then the createX method returns with thereference to the proxy 114.

After the remote object 124 and its corresponding proxy 114 areinstantiated, the application then invokes a method of the proxy 114passing an indication of an input parameter (“in”). The invoked methodmay invoke the client component to generate a request object thatincludes the object identifier of the proxy 114 (“2”), a methodidentifier, and the input parameter and to send to the server aninvocation request message based on the request object. Upon receivingthe invocation response message, the server component retrieves thereference for the remote object 124 from the ID table object and invokesthe identified method of the remote object 124 passing the inputparameter. When the method returns, the server component generates aresponse object that includes the object identifier of the remote object124 (“2”), the method identifier, and any output parameters. The servercomponent then sends to the client an invocation response message basedon the response object. Upon receiving the invocation response message,the client component extracts the output parameters and signals that themethod has returned to affect a synchronous or asynchronous invocationprocessing.

The application may then invoke the createX method and the createYmethod of the create proxy to effect creation of the remote object 125(“X3 object”) and the remote object 126 (“Y4 object”) at the server andthe corresponding proxy 115 (“X3 proxy”) and the corresponding proxy 116(“Y4 proxy”) at the client. The application can then invoke methods ofthe remote object 125 and the remote object 126 by invoking thecorresponding methods of the proxy 115 and the proxy 116.

The computing systems (e.g., clients, servers, client devices, serverdevices) on which the OORPC system may be implemented may include acentral processing unit, input devices, output devices (e.g., displaydevices and speakers), storage devices (e.g., memory and disk drives),network interfaces, graphics processing units, accelerometers, cellularradio link interfaces, global positioning system devices, and so on. Thecomputing systems may include servers of a data center, massivelyparallel systems, and so on. The computing systems may accesscomputer-readable media that include computer-readable storage media anddata transmission media. The computer-readable storage media aretangible storage means that do not include a transitory, propagatingsignal. Examples of computer-readable storage media include memory suchas primary memory, cache memory, and secondary memory (e.g., DVD) andother storage. The computer-readable storage media may have recorded onthem or may be encoded with computer-executable instructions or logicthat implements the OORPC system. The data transmission media are usedfor transmitting data via transitory, propagating signals or carrierwaves (e.g., electromagnetism) via a wired or wireless connection.

The OORPC system may be described in the general context ofcomputer-executable instructions, such as program modules andcomponents, executed by one or more computers, processors, or otherdevices. Generally, program modules or components include routines,programs, objects, data structures, and so on that perform particulartasks or implement particular data types. Typically, the functionalityof the program modules may be combined or distributed as desired invarious embodiments. Aspects of the OORPC system may be implemented inhardware using, for example, an application-specific integrated circuit(ASIC).

FIG. 2 is a flow diagram that illustrates the processing of a method ofa proxy that is synchronously invoked in some embodiments. A method 200,which is automatically generated by a code generator of the OORPCsystem, is passed one or more input parameters and returns one or moreoutput parameters. The method sends to the server an invocation requestmessage and receives an invocation response message. In block 202, themethod invokes a retrieve identifier method of the ID table objectpassing a reference to the proxy (“this”) to retrieve the objectidentifier of the proxy. The method stores the object identifier of theproxy in a request object. In block 204, the method adds the methodidentifier to the request object. In block 206, the method invokes astore parameters method of the request object to store the inputparameters. In block 208, the method sends to the server an invocationrequest message that is based on the request object. In block 210, themethod receives from the server an invocation response message andgenerates a response object. In block 212, the method invokes an extractparameters method of the response object to extract the outputparameters. The method then completes. In some embodiments, the methodmay invoke a client component to perform the processing of blocks202-212.

FIG. 3 is a flow diagram that illustrates processing of a receiverequest component of a server component in some embodiments. A receiverequest component 300 is invoked when an invocation request message isreceived from a client and is passed a request object that is based onthe invocation request message. The component invokes a method of aremote object and sends to the client an invocation response message. Inblock 302, the component extracts the object identifier of a remoteobject from the request object and invokes a retrieve reference methodof the ID table object, passing the object identifier, and receives areference to the remote object. In block 304, the component extracts themethod identifier from the request object. In block 306, the componentinvokes an extract parameters method of the request object to extractthe input parameters. In block 308, the component invokes the identifiermethod of the remote object, passing the input parameters and receivingany output parameters upon return. In block 310, the component generatesa response object that includes the object identifier, the methodidentifier, and output parameters. In block 312, the component sends tothe client an invocation response message that is based on the responseobject and then completes.

FIG. 4 is a flow diagram that illustrates the processing of an extractparameters method of a response object class for a response object of aclient component in some embodiments. An extract parameters method 400is invoked by a client component to extract the output parametersreturned by an invoked method. In block 402, the method selects the nextoutput parameter starting with the first. In decision block 404, if allthe output parameters have already been selected, then the methodcompletes, else the method continues at block 406. In decision block406, if the selected output parameter is an identifier of a remoteobject, then the method continues at block 410, else the methodcontinues at block 408. In block 408, the component stores the selectedoutput parameter as an output parameter and then loops to block 402 toselect the next output parameter. In block 410, the method invokes theretrieve reference method of the ID table object to retrieve a referenceto the remote object identified in the response object. In decisionblock 412, if the reference is null, then a proxy for the remote objecthas not been instantiated and the method continues at block 414, elsethe method continues at block 422. In block 414, the method instantiatesa proxy for the class of the remote object. The code generator for theOORPC system can identify the class of the remote object, and moregenerally the type of any parameter, from the signature of the invokedmethod. In blocks 416 and 418, the method creates an entry for the IDtable. In block 420, the method invokes an add entry method of the IDtable object to store the entry and then continues at block 422. Inblock 422, the component sets the output parameter to the returnedreference and then loops to block 402 to select the next outputparameter of the response object.

FIG. 5 is a flow diagram that illustrates the processing of a storeparameters method of a response object class for a response object of aserver component in some embodiments. A store parameters method 500 ispassed output parameters to be stored in the response object. In block502, the method selects the next output parameter. In decision block504, if all the output parameters have already been selected, then themethod completes, else the method continues at block 506. In decisionblock 506, if the output parameter is a reference to an object, then thecomponent continues at block at 508, else the component continues atblock 510. In block 508, the component invokes a retrieve ID method ofthe ID table object to retrieve the object identifier corresponding tothe reference and sets the output parameter to the reference. In block510, the component stores the output parameter in the response objectand then loops to block 502 to select the next output parameter.Although not illustrated, a request object also has an extractparameters method and a store parameters method that function in amanner similar to those of a response object.

FIGS. 6-9 are flow diagrams illustrating methods of an ID table objectclass in some embodiments. FIG. 6 is a flow diagram illustrating theprocessing of a retrieve ID method of an ID table object class in someembodiments. A retrieve ID method 600 is passed a reference to an objectand returns the object identifier corresponding to that reference. Inblock 602, the method selects the next entry of the ID table. Indecision block 604, if all the entries have already been selected, thenthe method returns a null value to indicate that an entry for thereference is not in the ID table, else the method continues at block606. In decision block 606, if the reference in the selected entrymatches the passed reference, then the method returns an indication ofthe object identifier of that entry, else the method loops to block 602to select the next entry of the ID table.

FIG. 7 is a flow diagram that illustrates the processing of a retrievereference method of an ID table object in some embodiments. A retrievereference method 700 is passed an object identifier and returns thereference corresponding to that object identifier. In block 702, themethod retrieves the next entry of the ID table. In decision block 704,if all the entries have already been selected, then the method returns anull value to indicate that an entry for the object identifier is not inthe ID table, else the method continues at block 706. In decision block706, if the object identifier of the selected entry matches the passedobject identifier, then the method returns the reference of the selectedentry, else the method loops to block 702 to select the next entry ofthe ID table.

FIG. 8 is a flow diagram that illustrates the processing of an add entrymethod of an ID table object that is passed a reference in someembodiments. An add entry method 800 is passed a reference to an object(i.e., proxy or remote object) and adds an entry to the ID table forthat reference if the ID table does not already contain an entry forthat reference. In block 802, the method invokes the retrieve ID methodof this ID table object passing the reference to retrieve the objectidentifier if the ID table contains an entry corresponding to thereference. In decision block 804, if the returned object identifier isnull, then the ID table does not contain a corresponding entry and themethod continues at block 806, else the method returns the objectidentifier. In block 806, the method sets the object identifier to anext object identifier field of the ID table object and increments thenext object identifier field. In blocks 808-810, the method initializesthe entry for the reference. In block 812, the method appends the entryto the ID table and then returns an indication of the object identifier.

FIG. 9 is a flow diagram that illustrates the processing of an add entrymethod of an ID table object that is passed an entry in someembodiments. An add entry method 900 is passed an entry that is to beadded to the ID table if the entry is not already in the ID table. Inblock 902, the method invokes a retrieve ID method of this ID tableobject passing the reference of the entry. In decision block 904, if theentry is null, then the ID table does not contain that entry and themethod continues at block 906, else the method returns. In block 906,the method adds the entry to the ID table and then returns.

In some embodiments, the OORPC system allows both the client and theserver to host remote objects that are accessed remotely by the other.The client and the server thus may be considered peers in the sense thatboth host remote objects. For example, if a document is being processedin a collaborative environment by multiple clients, each client mayregister an object with the server to receive event notifications ofchanges to the document. In such a case, a client may invoke a registermethod of the document proxy passing an event listener object that isinstantiated by the client. The client may maintain a proxy ID table formapping object identifiers to references to proxies for objects hostedremotely at the server and an object ID table that maps objectidentifiers to references to objects hosted locally by the client.Similarly, the server may maintain a proxy ID table for mapping objectidentifiers to references to proxies for objects hosted remotely by aclient and an object ID table that maps object identifiers to referencesto objects hosted locally by the server. The register method of thedocument proxy may add an entry for the event listener object to theobject ID table and include the object identifier of the entry as aninput parameter in the invocation request message for the registermethod. When the server receives the invocation request message, theserver component may search both the object ID table and proxy ID tablefor an entry with a matching object identifier. If such an entry isfound, the server component replaces the object identifier with thereference of the entry as the input parameter to the register method. Ifsuch an entry is not found, the server component instantiates an eventlistener proxy for the event listener object and adds an entry to theproxy ID table that maps the object identifier to the reference to theevent listener object proxy. The server component then invokes theregister method of the document remote object passing the reference tothe listener proxy. When the server component sends an event to theapplication, the server code invokes an event method of the listenerproxy, which sends to the client an invocation request message. When theclient receives the invocation request message, a client componentprocesses the invocation request message in much the same manner as theserver component of the server handles invocation request messages. Inthis way, both the client and the server can invoke methods of remoteobjects hosted remotely by the other.

In some embodiments, an object method of a remote object may have aninput parameter and/or an output parameter that is passed by value. Topass an input parameter by value, the proxy method of the proxycorresponding to the remote object retrieves the value for the inputparameter and adds the retrieved value to the invocation requestmessage. If the input parameter is itself a remote object hosted by theserver, then the proxy method may send an invocation request message tothe server to retrieve the value. Similarly, when returning an outputparameter by value, the object method retrieves the value of the outputparameter and adds the retrieved value to the invocation responsemessage. In some embodiments, an input parameter or an output parametermay be a data structure containing multiple objects. To pass an inputparameter that is such a data structure, the proxy method retrieve theobject identifier of each object in the data structure and add eachobject identifier to the invocation request message. For example, if thedata structure is an array, the proxy method for each element of thearray, selects the element, retrieves the object identifier of theselected element, and adds the retrieved object identifier to theinvocation request message. To pass an output parameter that is anarray, the object method processes the elements of the array in asimilar manner. The data structure of an input parameter or an outputparameter may contain an object hosted on the server and object hostedon the client. When processing such an input parameter, a proxy methodadds the object identifier of each object to the invocation requestmessage. Upon receiving, the invocation request message, the servercomponent retrieves the references to the objects from either the objectidentifier table or the proxy identifier table and invokes the objectmethod passing the retrieved references. The server component mayinstantiate a corresponding object or proxy if not yet instantiated.

FIG. 10 is a block diagram that illustrates an implementation of theOORPC system that supports peer hosting of remote objects in someembodiments. A client 1010 includes a proxy ID table object 1011 and anobject ID table object 1015. The proxy ID table object 1011 includes anID table that contains entries for proxies 1012, and the object ID tableobject 1015 includes an ID table that contains entries for remoteobjects 1016. A server 1020 includes an object ID table object 1021 anda proxy ID table object 1025. The object ID table object 1021 includesan ID table that contains an entry for each object 1022, and the proxyID table object 1025 includes an ID table that contains an entry foreach proxy 1026.

FIG. 11 is a block diagram that illustrates data structures that supportsynchronization of values of properties by the OORPC system in someembodiments. A client 1110 includes an ID table object 1111 with an IDtable that includes entries for proxies 1112 and 1113 for remote objectsof the remote object class X and that includes an entry for a proxy 1114for a remote object of the remote object class Y. Each proxy includes astatic data member for referencing a store object for its remote objectclass. Proxies 1112 and 1113 include a reference to a store object 1115for the remote object class X, and proxy 1114 includes a reference to astore object 1116 for the remote object class Y. The store object for aremote object class may include a method for each getter method of theremote object class that stores a value for a property locally in aproxy. A server 1120 includes an ID table object 1121 with an ID tablethat includes entries for remote objects 1122 and 1123 of the remoteobject class X and that includes an entry for an object 1124 of theremote object class Y. The server also includes a property table object1125 with a property table that includes an entry for each property ofeach remote object. Each entry includes an object identifier of theremote object, the last retrieved value of each property of the remoteobject, and a reference to a getter table for the remote object class ofthe remote object. In some embodiments, each entry may contain areference to a data structure that stores the last retrieved values forthe remote object. Also, the ID table and the property table may becombined into a single table. As illustrated, the first entry of theproperty table corresponds to the remote object 1122 and includes apointer to a getter table 1126 for the remote object class X. The gettertable 1126 includes an entry for each getter method 1128 and 1129 of theremote object class X. A getter table 1127 includes an entry for eachgetter method 1130 and 1131 of the remote object class Y. The entriespoint to code that invokes the corresponding getter method of a remoteobject to retrieve the value of a property.

Prior to sending a response invocation message, the server component mayselect each entry of the property table and invoke the getter methods ofthe remote object of each entry to retrieve the value of each property.If a value of a property returned by a getter method for an object isdifferent from the value for that property that is stored in theproperty table, the server component adds a property update to theinvocation response message. The property update includes the objectidentifier, a property identifier, and the new value. When the clientreceives the invocation response message, the client component processeseach property update. For each property update, the client componentretrieves the reference to the proxy corresponding to the objectidentifier of the property update. The client component retrieves thereference to the store object from the proxy and invokes thecorresponding store method for that property of the store object passingan indication of the reference. The store method then stores the valueof the property in the proxy. In some embodiments, each property updatemay contain the values for all the changed properties of a remoteobject. That is, the invocation response message contains only oneproperty update for a remote object, rather than a separate propertyupdate for each changed property of the remote object.

FIG. 12 is a flow diagram that illustrates the processing of a getproperty values component of a server component in some embodiments. Aget property values component 1200 is invoked to add a property updateto an invocation response message for each property of each remoteobject whose value has changed. In block 1202, the component selects thenext entry of the property table. In decision block 1204, if all theentries have already been selected, then the component completes, elsethe component continues at block 1206. In block 1206, the componentinvokes the retrieve reference method of the ID table object to retrievethe reference corresponding to the object identifier of the selectedentry. In blocks 1208-1218, the component loops processing each propertyof the referenced remote object. In block 1208, the component selectsthe next getter method from the getter table referenced by the selectedentry. In decision block 1210, if all the getter methods have alreadybeen selected, then the component loops to block 1202 to select the nextentry in the property table, else the component continues at block 1212.In block 1212, the component invokes the selected getter method of thereferenced remote object. In decision block 1214, if the current valueof the property is the same as the value in the selected entry for theproperty, then the component loops to block 1208 to select the nextgetter method, else the component continues at block 1216. In block1216, the component sets the value in the entry for the property to thecurrent value. In block 1218, the component adds a property update withthe object identifier, the property identifier, and the current value ofthe property to the invocation response message and then loops to block1208 to select the next getter method.

FIG. 13 is a flow diagram that illustrates the processing of a storeproperty values component of a client component in some embodiments. Astore property values component 1300 is invoked when an invocationresponse message is received that includes property updates and updatesthe locally stored values for the properties. In block 1302, thecomponent selects the next property update of the invocation responsemessage. In decision block 1304, if all the property updates havealready been selected, then the component completes, else the componentcontinues at block 1306. In block 1306, the component invokes theretrieve reference method of the ID table object, passing the objectidentifier of the selected entry, and receives a reference to thecorresponding proxy. In block 1308, the component invokes a store methodof the store object referenced by a static data member of the proxypassing the value of the entry. The component then loops to block 1302to select the next property update entry of the response invocationmessage. A store object may have a separate store method generated tohandle each property. Alternatively, the store object may have a singlestore method that accesses a table with an entry for each property withinformation such as type of object and name of property.

FIG. 14 is a flow diagram that illustrates a code generator of the OORPCsystem for automatically generating code for proxy classes in someembodiments. A proxy code component 1400 is passed an interface for eachclass of objects hosted by a server and generates the proxy classes(e.g., JavaScript). In block 1402, the component selects the nextinterface. In decision block 1404, if all the interfaces have alreadybeen selected, then the component completes, else the componentcontinues at block 1406. In block 1406, the component generates initialcode for the proxy class, which may include a class template thatincludes the name of the class, beginning and ending symbols of theclass (e.g., parentheses), and so on. In blocks 1408-1412, the componentloops processing each method of the interface that is not a gettermethod. In block 1408, the component selects the next method. Indecision block 1410, if all the methods have already been selected, thenthe component continues at block 1414, else the component continues atblock 1412. In block 1412, the component generates code for the selectedmethod of the proxy class and then loops to block 1408 to select thenext method. In block 1414, the component invokes a process proxyproperties component of the code generator passing an indication of theselected interface to generate code for a store class for the proxyclass. The component then loops to block 1402 to select the nextinterface.

FIG. 15 is a flow diagram that illustrates the processing of a processproxy properties component of the code generator in some embodiments. Aprocess proxy properties component 1500 is invoked to generate a storeclass for a proxy class and add a static data member to the proxy classfor storing a reference to a store object for the proxy class. In block1502, the component generates the initial code for the store class. Inblock 1504, the component adds to the proxy class a static data memberfor referencing a store object. In block 1506, the component selects thenext property of the interface. In decision block 1508, if all theproperties of the interface have already been selected, then thecomponent completes, else the component continues at block 1510. Inblock 1510, the component generates code for a setter method of theproxy class for the selected property that sends an invocation requestmessage to a server. In block 1512, the component generates code for agetter method of the proxy class for the selected property thatretrieves the local value of the property. In block 1514, the componentgenerates code for a store method of the store class for storing in theproxy a value of the selected property that is received in an invocationresponse message and then loops to block 1506 to select the nextproperty of the interface.

In some embodiments, a code generator of the OORPC system mayautomatically generate a server component for a server to supportinvocation of remote objects. The code generator may be provided theinterfaces for the remote objects hosted by the server. The codegenerator generates code to receive from a client an invocation requestmessage and to invoke the identified remote object method of theidentified remote object passing the identified input parameter. Thecode generator also generates code to, after the invoked remote objectmethod returns, send to the client an invocation response message withan object identifier of the remote object, a method identifier of theremote object methods, and an output parameter returned by the invokedremote object method. The code generator may also automatically generatethe code that supports the synchronization of property values based onthe interfaces.

FIGS. 16 and 17 are flow diagrams that illustrate the deferring ofinvocation requests in some embodiments. FIG. 16 is a flow diagram thatillustrates the processing of a send request component of a clientcomponent in some embodiments. A send request component 1600 is invokedpassing an invocation request (e.g., via a request object) to invoke amethod of a remote object. The component sends to a server an invocationrequest message with any queued invocation requests when the invocationof the method is not deferrable. In block 1602, the component appendsthe invocation request to a request queue. In decision block 1604, ifthe invocation of the method is deferrable, then the componentcompletes, else the component continues at block 1606. In block 1606,the component adds the invocation requests of the invocation requestqueue to an invocation request message. In block 1608, the componentsends to the server the invocation request message. In block 1610, thecomponent empties the request queue and then completes.

FIG. 17 is a flow diagram that illustrates the processing of a receiverequest component of a server component in some embodiments. A receiverequest component 1700 is invoked when a server component receives aninvocation request message. In block 1702, the component selects thenext invocation request of the invocation request message. In decisionblock 1704, if all the invocation requests have already been selected,then the component completes, else the component continues at block1706. In block 1706, the component processes the selected invocationrequest by invoking the method of the remote object identified by theinvocation request. The component then loops to block 1702 to select thenext invocation request.

The following paragraphs describe various embodiments of aspects of theOORPC system. An implementation of the OORPC system may employ anycombination of the embodiments. The processing described below may beperformed by a computing device with a processor that executescomputer-executable instructions stored on a computer-readable storagemedium that implements the OORPC system.

In some embodiments, a method performed by a client is provided forinvoking a remote object member function of a remote object of a remoteobject class where the remote object is hosted by a server. Undercontrol of a browser, the method performs the following. The methodretrieves a web page that includes the application. Under control of theapplication, the method instantiates a proxy of a proxy class where theproxy class includes a proxy member function with a same signature asthe remote object member function. The method associates an objectidentifier with the proxy where the object identifier is for use inidentifying the remote object to the server. The method invokes theproxy member function of the proxy object. Under control of the invokedproxy member function, the method sends to the server an invocationrequest message that includes the object identifier that is associatedwith the proxy and an identifier of the remote object member function.The application relies on functionality provided by the browser withoutthe need for the browser to access add-on functionality when executingthe application. In some embodiments, the method further sends to theserver an invocation request message that requests to invoke a memberfunction of a create remote object to instantiate the remote object. Insome embodiments, the method further, under control of the application,receives from the server an invocation response message that indicatesthe remote object has been instantiated. In some embodiments, theinvocation response message includes the object identifier that isassigned to the remote object by the server. In some embodiments, theinvocation request message includes the object identifier that isassigned to the remote object by the client. In some embodiments, theinvocation request message includes an input parameter that is passed tothe proxy member function. In some embodiments, the invocation responsemessage includes an output parameter to be returned by the proxy memberfunction. In some embodiments, the proxy is identified by a proxyreference and further comprising associating the proxy reference withthe object identifier. In some embodiments, the associating includesadding to an object identifier table an entry that includes the proxyreference and the object identifier. In some embodiments, the remoteobject class and proxy class are implemented in different programminglanguages. In some embodiments, the proxy class is automaticallygenerated based on an interface definition for the remote object class,the proxy class including an implementation of the proxy memberfunction. In some embodiments, the invocation of the proxy memberfunction is an asynchronous invocation.

In some embodiments, a method performed by a computing system isprovided for generating proxy classes for an application executing at aclient to access remote objects of remote object classes hosted by aserver The method accesses interfaces of the remote object classes whereeach interface includes a signature of a remote object member functionof the remote class. For each remote object class, the method generatesa proxy class for the remote object class. The proxy class includes anproxy member function for each remote object member function of theremote object class. Each proxy member function of the proxy class isgenerated to, upon invocation of the proxy member function, send to theserver an invocation request message that an object identifier of aremote object, a member function identifier of the remote object memberfunction, and an input parameter passed to the proxy member function.The method provides code to, after an invocation response message isreceived from the server, extract an object identifier of a remoteobject, a member function identifier of the remote object memberfunction, and an output parameter from the invocation response messageand indicate that the invocation of the remote object member functionhas completed. In some embodiments, the method further generates aserver component for the server wherein the server component isgenerated, based on the interfaces of the remote objects hosted by, toreceive from the client an invocation request message, invoke theidentified remote object member function of the identified remote objectpassing the identified input parameter and after the invoked remoteobject member function returns, send to the client an invocationresponse message with an object identifier of the remote object, amember function identifier of the remote object member function, and anoutput parameter returned by the invoked remote object member function.In some embodiments, the code of the application relies on functionalityprovided by the browser without the need for the browser to accessadd-on functionality when executing the application.

In some embodiments, a client is provided that is configured to enablean application executed by an application execution engine of a programto invoke a remote object member function of a remote object of a remoteobject class hosted by a server. The client includes a processor toexecute computer-executable instructions and a computer-readable storagemedium storing computer-executable instructions that, when executed bythe processor, control the client to perform the following processing.The processing instantiates a proxy of a proxy class where the proxyclass includes a proxy member function with a same signature as theremote object member function. The processing associates an objectidentifier with the proxy where the object identifier is for use inidentifying the remote object to a server. The processing invokes theproxy member function of the proxy. Under control of the invoked proxymember function, the processing sends to the server an invocationrequest message that includes an object identifier that identifies theremote object and a member function identifier that identifies theremote object member function. In some embodiments, the applicationrelies on functionality provided by the program without the need for theprogram to access add-on functionality when executing the applicationand the proxy class of the application is automatically generated froman interface of the remote object class to support accessing by theclient of the remote object. In some embodiments, the processing furthersends to the server an invocation request message that requests toinstantiate an instance of the remote object class and receive from theserver an invocation response message that indicates that the remoteobject has been instantiated. In some embodiments, the processinginstantiates a create proxy with a member function that when invokeddirects the instantiating of the proxy and the sending of the invocationrequest message. In some embodiments, the invocation response messageincludes the object identifier. In some embodiments, the program is asbrowser, and the application is downloaded and executed in response to auser accessing a web page via the browser.

In some embodiments, a client is provided that is configured to enablean application executed by a program with an application executionengine to invoke a remote object member function of a remote object of aremote object class hosted by a server and to support invoking by theserver of a local object member function of a local object of a localobject class hosted by the client. The client includes a processor thatexecutes computer-executable instructions and a computer-readablestorage medium storing computer-executable instructions that, whenexecuted by the processor, control the client to perform the followingprocessing. Under control of the application executed by the program,the processing instantiates a proxy of a proxy class, where the proxyclass including a proxy member function with a same signature as theremote object member function. The processing instantiates a localobject of the local object class. The processing associates a remoteobject identifier with a proxy reference to the proxy and a local objectidentifier with a local object reference to the local object. Undercontrol of the invoked proxy member function, the processing sends tothe server an invocation request message that includes the remote objectidentifier that identifies the remote object and a member functionidentifier that identifies the remote object member function. Uponreceiving from the server an invocation request message that includesthe local object identifier and identifies the local object memberfunction, the processing retrieves the local object reference associatedwith to the included local object identifier and invoke the local objectmember function of the local object referenced by the retrieved localobject reference.

In some embodiments, a method performed by a client for synchronizing aproperty value is provided. The method instantiates a proxy of a proxyclass corresponding to a remote object of a remote object class. Theremote object is instantiated at a server. The proxy class specifies aproperty with a proxy getter. The proxy getter for the proxy is forretrieving a value for the property that is stored in the proxy. Themethod sends the server an invocation request message to invoke a remoteobject member function of a remote object. The method receives from theserver an invocation response message to the invocation request message.When the invocation response message includes a property update, themethod extracts from the invocation response message the value of theproperty from the property update and stores the extracted value in theproxy. When the proxy getter for the property is invoked, the methodallows the value of the property to be retrieved from the proxy withouthaving to send an invocation request message to the server. In someembodiments, the proxy is part of an application that is executed by abrowser. In some embodiments, the sending to the server and receivingfrom the server are via HTTP messages. In some embodiments, the proxyclass includes a static reference to a store object of a store classwith a store member function for the property and wherein the extractingand storing are performed by the store member function. In someembodiments, the store class includes a store member function for eachproperty of the proxy class. In some embodiments, the store classincludes a getter table that maps an identifier of the property to anidentifier of the store member function of the store class for thatproperty for storing the extracted value and to an identifier of a typeof the property. In some embodiments, the store member function ispassed a reference to a proxy and performs the extracting of the valueof the property based on the type of the property and storing the valuein the referenced proxy. In some embodiments, the store member functionis passed the identifier of the proxy. In some embodiments, theinvocation response message includes values for multiple properties ofthe proxy. In some embodiments, the invocation response message includesvalues for multiple properties of different proxies. In someembodiments, the invocation response message includes values for onlythose properties whose value has changed since a prior invocationresponse message was sent by the server.

In some embodiments, a method performed by a server for synchronizing aproperty value stored at a client is provided. The method receives fromthe client a request to invoke a remote object member function of aremote object hosted by the server. The method invokes the remote objectmember function of the remote object. After invoking the remote objectmember function of the remote object, the method retrieves a value for aproperty of the remote object. When the retrieved value is not the sameas a last retrieved value for the property, the method adds to aninvocation response message an object identifier of the remote object, aproperty identifier of the property, and the retrieved value. The methodsends to the client the invocation response message to indicate that theremote object member function was invoked and that the value for theproperty has changed so that a getter member function for the propertyof a proxy of the client for the remote object can retrieve the value ofthe property locally with accessing the server. In some embodiments, theretrieving and adding are performed for multiple properties. In someembodiments, the multiple properties include properties of differentremote objects. In some embodiments, the retrieving and adding areperformed for each invocation response message that is to be sent toindicate that a remote object member function of a remote object wasinvoked.

In some embodiments, a method that is performed by a computing system isprovided for supporting synchronization of values of properties ofremote objects of remote object classes with values of properties ofproxies of proxy classes. The method inputs a description of aninterface for each remote object class. For each interface for remoteobject class, the method generates code for the proxy class. The methodgenerates code for each proxy member function of the proxy class to sendan invocation request message to invoke the corresponding remote objectmember function on a corresponding remote object. The method generatescode for each proxy getter member function of a property of the proxyclass to retrieve and return a value of the property that is storedlocally at a proxy of the proxy class without accessing thecorresponding remote object. The method generating code for storingvalues of the properties of the proxy class received from the server sothat each proxy getter member function of a property of the proxy classcan retrieve a locally stored value for the property. In someembodiments, the method further, for each proxy class, adds to the proxyclass a static reference to the code for storing values of theproperties. In some embodiments, the code for storing the values of theproperties is implemented as part of a store class. In some embodiments,the store class includes a table that maps, for each property of theproxy class, an identifier of the property to a store member functionfor storing a value for that property so that the value can be retrievedby the proxy getter member function of that property. In someembodiments, the identifier of the property is further mapped to anindication of a type of the property for use in extracting the value ofthe property from an invocation response message received from server.

In some embodiments, a method performed by a client for sendinginvocation requests of an application to remote objects of a server isprovided. The method receives invocation requests. Each invocationrequest is from a proxy of a proxy class of the applicationcorresponding to a remote object of a remote object class. For eachreceived invocation request, when the invocation request is deferrable,the method stores the invocation request. When the invocation request isnot deferrable, the method sends to the server an invocation requestmessage that includes each stored invocation request not previously sentand the received invocation request. The method receives from the serverinvocation response messages. Each invocation response message is inresponse to an invocation request message that included one or moreinvocation requests. At least one invocation response message includesmultiple invocation responses. For each invocation response of areceived invocation response message, when the invocation responseincludes an output parameter, the method extracts the output parameterfrom the invocation response. The method provides to the application anindication that the invocation response has been received and anyextracted output parameter. In some embodiments, the invocation requestmessage indicates an order in which the invocation requests werereceived. In some embodiments, the invocation responses of an invocationresponse message are processed in an order in which the correspondinginvocation requests were received. In some embodiments, the invocationrequests are asynchronous invocation requests. In some embodiments, whenan invocation request has been stored for more than a designated amountof time, the method sends an invocation request message that includesthe invocation request. In some embodiments, in response to receivingfrom the application a request to send an unsent invocation request, themethod further sends an invocation request message that includes theinvocation request. In some embodiments, invocation requests arereceived for remote objects hosted by different servers and wherein aninvocation request message that is sent to a server includes onlyinvocation requests for remote objects hosted by that server. In someembodiments, the application is executed under control of a browser.

In some embodiments, a client is provided for sending invocationrequests of an application to invoke member functions of remote objectshosted by a server. The client includes a processor that executes thecomputer-executable instructions and a computer-readable storage mediumstoring computer-executable instructions that, when executed by theprocessor, control the client to perform the following processing. Theprocessing queues invocation requests. Each invocation request is from aproxy of a proxy class of the application corresponding to a remoteobject of a remote object class of the application. The invocationrequest is for invoking a remote object member function of the remoteobject. When a send invocation request criterion is satisfied, theprocessing sends to the server an invocation request message thatincludes each queued invocation request. The processing indicates thateach queued invocation request is no longer queued. The processingreceives from the server an invocation response message that is inresponse to the invocation request message. For each invocation responseof the received invocation response message, the processing provides tothe application an indication that the invocation response has beenreceived. In some embodiments, the send invocation request criterion issatisfied when an invocation request is received that is to not bequeued. In some embodiments, the send invocation request criterion issatisfied when an invocation request has been stored for more than adesignated amount of time. In some embodiments, the send invocationrequest criterion is satisfied when a request is received from theapplication to send queued invocation requests. In some embodiments, heinvocation request message indicates an order in which the invocationrequests were generated by the application. In some embodiments, theinvocation responses of the invocation response message are processed inan order in which the corresponding invocation requests were generated.In some embodiments, the invocation requests are asynchronous invocationrequests. In some embodiments, the invocation requests are received forremote objects hosted by different servers and wherein an invocationrequest message that is sent to a server includes only invocationrequests for remote objects hosted by that server. In some embodiments,the application is executed under control of a program with anapplication execution engine.

In some embodiments, a method performed by a server for processinginvocation requests of an application. The method receives from a clientan invocation request message that includes invocation requests. Eachinvocation request is from a proxy of a proxy class of the applicationcorresponding to a remote object of a remote object class of theapplication. The invocation request is for invoking a remote objectmember function of the remote object. For each invocation request of theinvocation request message, the processes the invocation request. Theprocessing includes extracting from the invocation request an objectidentifier of a remote object, a member function identifier of a remoteobject member function, and an input parameter. The processing invokesthe identified remote object member function of the identified remoteobject passing the input parameter. Upon return from the invoked remoteobject member function, the processing stores an invocation response forthe invocation request that includes an output parameter returned by theinvoked remote object member function. After processing the invocationrequests, the method sends to the client an invocation response messagethat includes the invocation responses. In some embodiments, theinvocation requests are processed in an order specified by theinvocation request message. In some embodiments, the invocation requestscorresponding to the invocation responses are identifiable from theinvocation responses. In some embodiments,

Although the subject matter has been described in language specific tostructural features and/or acts, it is to be understood that the subjectmatter defined in the appended claims is not necessarily limited to thespecific features or acts described above. Rather, the specific featuresand acts described above are disclosed as example forms of implementingthe claims. For example, although the OORPC system is describesprimarily in the context of a web browser that executes an application,the OORPC may be used in other contexts. For example, a customerrelationship management (“CRM”) system may allow applications to bedeveloped to customize the CRM system. In such a case, a client-sidecomponent of the CRM system executes applications that access objectshosted by a server that has a server-side component of the CRM system.Web browsers, CRM system, and other programs that execute suchapplications may be referred as a program having an applicationexecution engine. Accordingly, the invention is not limited except as bythe appended claims.

The invention claimed is:
 1. A method performed by a client forsynchronizing a property value, the method comprising: instantiating aproxy of a proxy class corresponding to a remote object of a remoteobject class, the remote object being instantiated at a server, theproxy class specifying a property with a proxy getter and including astatic reference to a store object of a store class that includes astore member function for each of a plurality of properties of the proxyclass, the proxy getter for the proxy retrieving a value for theproperty that is stored in the proxy; sending to the server aninvocation request message to invoke a remote object member function ofa remote object; receiving from the server an invocation responsemessage to the invocation request message; and when the invocationresponse message includes a property update, retrieving from theproperty update, by the store member function, an object identifier ofthe remote object and an updated value of the property; and storing, bythe store member function, the updated value in the proxy correspondingto the object identifier, wherein when the proxy getter for the propertyis invoked, the updated value of the property can be retrieved from theproxy without having to send an invocation request message to theserver.
 2. The method of claim 1 wherein the proxy is part of anapplication that is executed by a browser.
 3. The method of claim 2wherein the sending to the server and receiving from the server are viaHTTP messages.
 4. The method of claim 1 wherein the store class includesa getter table that maps an identifier of the property to an identifierof the store member function of the store class for that property forstoring the updated value and to an identifier of a type of theproperty.
 5. The method of claim 4 wherein the store member function ispassed a reference to a proxy and performs the retrieving of the updatedvalue of the property based on the type of the property and the value inthe referenced proxy.
 6. The method of claim 4 wherein the reference tothe proxy is an identifier of the proxy.
 7. The method of claim 1wherein the invocation response message includes updated values formultiple properties of the proxy.
 8. The method of claim 1 wherein theinvocation response message includes values for multiple properties ofdifferent proxies.
 9. The method of claim 1 wherein the invocationresponse message includes values for only those properties whose valuehas changed since a prior invocation response message was sent by theserver.
 10. A method performed by a server for synchronizing a propertyvalue stored at a client, the method comprising: receiving from theclient a request to invoke a remote object member function of a remoteobject hosted by the server; invoking the remote object member functionof the remote object; after invoking the remote object member functionof the remote object, retrieving an updated value for a property of theremote object; and when the updated value is not the same as a lastretrieved value for the property, adding to an invocation responsemessage a property update that includes an object identifier of theremote object, a property identifier of the property, and the updatedvalue; and sending to the client the invocation response message toindicate that the remote object member function was invoked and that thevalue for the property has changed so that a getter member function forthe property of a proxy of the client for the remote object can retrievethe updated value of the property locally without accessing the server,the remote object corresponding to a proxy of a proxy class instantiatedat the client, the proxy class including a static reference to a storeobject of a store class that includes a store member function for eachof a plurality of properties of the proxy class, wherein the storemember function is used to store the updated value of the property inthe proxy.
 11. The method of claim 10 wherein the retrieving and addingare performed for multiple properties.
 12. The method of claim 11wherein the multiple properties include properties of different remoteobjects.
 13. The method of claim 10 wherein the retrieving and addingare performed for each invocation response message that is to be sent toindicate that a remote object member function of a remote object wasinvoked.
 14. A method performed by a computing system for supportingsynchronization of values of properties of remote objects of remoteobject classes with values of properties of proxies of proxy classes,the method comprising: inputting a description of an interface for eachremote object class; and for each interface for each remote objectclass, generating code for a proxy class by: generating code for eachproxy member function of the proxy class to send an invocation requestmessage to invoke a corresponding remote object member function on acorresponding remote object; generating code for each proxy gettermember function of a property of the proxy class to retrieve an objectidentifier of the remote object and an updated value of the propertyfrom an invocation response message received from the server, theupdated value being stored locally at a proxy of the proxy class withoutaccessing the corresponding remote object; and generating code forstoring values of the properties of the proxy class received from theserver so that each proxy getter member function of a property of theproxy class can retrieve a locally stored value for the property, eachproxy class including a static reference to a store object of a storeclass, the store class including a getter table that maps, for eachproperty of the proxy class, an identifier of the property to a storemember function for storing a value for that property and to anindication of a type of the property, wherein the store member functionis used to store the updated value of the property in the proxy.
 15. Themethod of claim 14 further comprising, for each proxy class, adding tothe proxy class a static reference to the code for storing values of theproperties.
 16. The method of claim 15 wherein the code for storing theupdated values of the properties is implemented as part of the storeclass.
 17. The method of claim 16 wherein the updated value of theproperty can be retrieved by the proxy getter member function of thatproperty.
 18. The method of claim 17 wherein the identifier of theproperty mapped to the indication of the type of the property is used inextracting the value of the property from the invocation responsemessage received from the server.
 19. The method of claim 14, whereinthe store member function is passed a reference to a proxy and performsthe retrieving of the updated value of the property based on the type ofthe property and the value in the referenced proxy.
 20. The method ofclaim 19, wherein the reference to the proxy is an identifier of theproxy.